JP5251468B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve, and is suitably applied to, for example, a fuel injection valve that injects and supplies fuel to an internal combustion engine.

  As a prior art, there is a fuel injection valve disclosed in Patent Document 1 below. The fuel injection valve includes a valve body that opens and closes an ejection hole, a movable core that is provided so as to be relatively movable in the axial direction with respect to the valve body, and is magnetically attracted toward the counter-ejection hole side by energizing a coil. A regulating means for projecting radially outward at the end of the valve body on the side opposite to the ejection hole and regulating the retreat limit position of the movable core toward the side opposite to the ejection hole; and a first means for biasing the valve body toward the ejection hole A spring, a second spring that urges the movable core toward the anti-ejection hole side with a smaller spring load than the first spring, and a housing that houses these components are provided.

A fuel passage toward the injection hole is formed between the valve body and the valve body in the housing. In the valve body, fuel is supplied to the fuel passage from the upstream fuel passage. A communication path as a supply path is formed. And the downstream end of a communicating path is opening to the fuel channel | path which becomes an ejection hole side rather than the ejection hole side seat surface of a 2nd spring.
Utility Model Registration No. 2568515

  However, in the above-described conventional fuel injection valve, the downstream end of the communication passage opens into a fuel passage having a relatively small volume. Therefore, when the valve element opens and closes the ejection hole, There is a problem that pulsation tends to occur in the fuel pressure. When pulsation occurs in the fuel pressure, there arises a problem that it is difficult to obtain the stability and reproducibility of the fuel injection amount and the fuel spray shape.

  The present invention has been made in view of the above points, and an object thereof is to provide a fuel injection valve capable of reducing pulsation of internal fuel pressure.

In order to achieve the above object, in the invention described in claim 1,
By back and forth displacement in the axial direction away seated against the valve seat, a valve member for intermittently jetting the fuel from the injection hole by opening and closing the injection hole,
An end of the valve member on the side opposite to the injection hole is provided so as to be movable relative to the valve member in the axial direction. When the coil is energized, it is magnetically attracted toward the fixed core on the side opposite to the injection hole in the axial direction. A movable core,
A stopper that protrudes radially outward at the end of the valve member on the side of the anti-injection hole, and that can come into contact with the surface of the movable core on the side of the anti-injection hole;
An elastic member provided on the nozzle hole side of the movable core and biasing the movable core toward the counter nozzle hole;
A housing for accommodating the movable core in an axially movable manner,
The housing has a small inner diameter portion and a large inner diameter portion which is provided on the counter-injection hole side from the small inner diameter portion and has a larger inner diameter than the small inner diameter portion, and is directed to the injection hole between the small inner diameter portion and the valve member. While the fuel passage is formed, the stepped surface portion between the large inner diameter portion and the small inner diameter portion communicating directly with each other serves as a seat surface that supports the end portion on the injection hole side of the elastic member,
The valve member is a fuel injection valve in which a fuel supply passage to be supplied to the fuel passage is formed.
The relative movement of the valve member toward the anti-injection hole with respect to the movable core that collides with the fixed core when the valve is opened is defined as overshoot.
The relative movement of the movable core toward the nozzle hole with respect to the valve member seated on the valve seat when the valve is closed is defined as undershoot.
Regardless of the axial displacement position of the valve member that accompanies the reciprocal displacement, the downstream end of the supply passage includes the stepped surface portion in the axial direction of the valve member and the end surface on the injection hole side of the movable core , both during overshoot and undershoot. It is characterized by opening at a portion between.

According to this, the opening position of the downstream end of the supply passage formed in the valve member, regardless of the displacement position of the valve member, always be between the stepped surface portion and the injection hole side end face of the movable core. That is, the downstream end of the supply passage always opens toward the elastic member storage space inside the large inner diameter portion of the housing. Thus, by opening the downstream end of the supply passage in the elastic member storage space inside the large inner diameter portion having a larger volume than the fuel passage inside the small inner diameter portion, the fuel pressure when the valve member opens and closes is increased. Pulsation can be reduced.

In the invention according to claim 2, the supply passage in the valve member includes an upstream passage extending in the axial direction and a plurality of downstream passages extending to the downstream end by being connected to intersect with the upstream passage. The total cross-sectional area of these downstream passages is larger than the cross-sectional area of the upstream passage.

According to this, the supply passage has a structure bent in the valve member, the connection point between the upstream passage and a plurality of downstream passage, the cross-sectional area of the upstream side passage towards the total cross-sectional area thereof downstream passage It is getting bigger. Therefore, the pulsation of the fuel pressure when the valve body opens and closes can be further reduced.

It is preferable as defined in claim 2, by the supply passage has a plurality of downstream passage, the total cross-sectional area thereof downstream passage is easily formed the cross-sectional area larger configuration of the upstream passage Can do.

  Embodiments to which the present invention is applied will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an injector 10 according to an embodiment to which the present invention is applied. 2 is a cross-sectional view showing the main structure of the injector 10. FIG. 3 is a time chart showing the relationship between the energized state of the coil, the needle position, and the movable core position. FIG. The energized state, (b) shows the needle position, and (c) shows the movable core position.

  An injector 10 shown in FIG. 1 is a fuel injection valve, and is applied to, for example, a direct injection type gasoline engine. When the injector 10 is applied to a direct injection type gasoline engine, the injector 10 is mounted on an engine head (not shown).

  The injector 10 includes a cylindrical member 11 extending in a predetermined axial direction Z (opening / closing direction), an inlet member 12 provided at one end of the axial direction Z of the cylindrical member 11, and a nozzle holder provided at the other end of the axial direction Z of the cylindrical member 11. 13, a needle 14 that is accommodated so as to be reciprocally movable in the axial direction Z inside the injector 10, and a drive unit 15 that drives the needle 14.

  Hereinafter, as the direction of the injector 10, the direction in which the tubular member 11 extends is referred to as an axial direction Z (vertical direction in FIG. 1), and one of the axial directions Z is a valve opening direction Z1 (upward in FIG. 1, opposite to the injection hole side). The other of the axial directions Z may be referred to as the valve closing direction Z2 (downward in FIG. 1, the nozzle hole side).

  The cylindrical member 11 is formed in a cylindrical shape having substantially the same inner diameter in the axial direction Z. The cylindrical member 11 has a magnetic part 16 having magnetism and a nonmagnetic part 17 having no magnetism. The magnetic part 16 is located in the valve opening direction Z1 with respect to the nonmagnetic part 17. Therefore, the end portion of the cylindrical member 11 located in the valve closing direction Z <b> 2 becomes the nonmagnetic portion 17. Such a nonmagnetic portion 17 prevents a magnetic short circuit between the magnetic portion 16 and the nozzle holder 13. The magnetic part 16 and the nonmagnetic part 17 are integrally connected by, for example, laser welding. Further, the cylindrical member 11 may be partly magnetized or non-magnetic by, for example, thermal processing after being integrally formed.

  The inlet member 12 is provided at the end of the cylindrical member 11 located in the valve opening direction Z1. The inlet member 12 is press-fitted on the inner peripheral side of the cylindrical member 11. The inlet member 12 has a fuel inlet 18 penetrating in the axial direction Z. Fuel is supplied to the fuel inlet 18 from a fuel pump (not shown). A fuel filter 19 is provided at the fuel inlet 18. The fuel filter 19 removes foreign matters contained in the fuel. Therefore, the fuel supplied to the fuel inlet 18 flows into the inner peripheral side of the cylindrical member 11 via the fuel filter 19.

  The nozzle holder 13 is provided at the end of the cylindrical member 11 located in the valve closing direction Z2. Therefore, the cylindrical member 11 and the nozzle holder 13 cooperate to constitute a cylindrical housing. The nozzle holder 13 has magnetism. Therefore, the nonmagnetic portion 17 of the cylindrical member 11 is located between the magnetic portion 16 and the magnetic nozzle holder 13 in the axial direction Z. The nozzle holder 13 is formed in a cylindrical shape.

  The nozzle holder 13 has a large-diameter portion 20, a medium-diameter portion 21, a small-diameter portion 22, and a mounting portion 23 that are substantially coaxial and have different inner diameters. Of the three diameter portions 20 to 22, the large diameter portion 20 has the largest inner diameter, the medium diameter portion 21 has the next largest inner diameter, and the small diameter portion 22 has the smallest inner diameter. Further, the positional relationship of the three diameter portions 20 to 22 is such that the large diameter portion 20 is located at the end portion in the valve opening direction Z1, the small diameter portion 22 is located at the end portion in the valve closing direction Z2, and the medium diameter portion 21 is the shaft. It is located in the center of the direction Z, that is, between the large diameter portion 20 and the small diameter portion 22. The inner diameter of the large-diameter portion 20 is approximately equal to the inner diameter of the cylindrical member 11 and is disposed so as to be substantially coaxial with the cylindrical member 11. The attachment portion 23 is provided at the end of the small diameter portion 22 located in the valve closing direction Z2. Therefore, the end portion of the nozzle holder 13 in the valve closing direction Z <b> 2 becomes the attachment portion 23. The attachment portion 23 is provided with a nozzle body 24.

  The nozzle body 24 is formed in a cylindrical shape, and is fixed to the mounting portion 23 of the nozzle holder 13 by, for example, press fitting or welding. The inner wall surface of the nozzle body 24 is inclined so that the inner diameter becomes smaller toward the valve closing direction Z2, and is formed in a so-called sharp shape. A nozzle hole 25 that penetrates the nozzle body 24 in the axial direction Z and communicates the inner wall surface and the outer wall surface is formed at the tip of the nozzle body 24. The inner wall surface around the nozzle hole 25 functions as a valve seat 29.

  The needle 14 is a valve member and is accommodated on the inner peripheral side of the cylinder member 11, the nozzle holder 13, and the nozzle body 24 so as to be reciprocally movable in the axial direction Z. The needle 14 reciprocates in the axial direction Z to open and close the injection hole 25 and intermittently inject fuel from the injection hole 25. The needle 14 is disposed substantially coaxially with the nozzle body 24. The needle 14 has a shaft portion 26, a stopper 27, and a seal portion 28. The needle 14 has a stopper 27 provided at one end side of the shaft portion 26, that is, an end portion on the fuel inlet 18 side (opposite injection hole side) so as to protrude radially outward. Further, the needle 14 has a seal portion 28 at the other end side of the shaft portion 26, that is, at the end opposite to the fuel inlet 18 (injection hole side). The seal portion 28 can be seated on a valve seat 29 formed on the nozzle body 24.

  The needle 14 has an inflow hole 30 and a communication hole 31 through which fuel flows. Specifically, the needle 14 is formed with an inflow hole 30 that is an upstream-side passage and a communication hole 31 that is a downstream-side passage connected to the downstream side of the inflow hole 30. A configuration including the inflow hole 30 and the communication hole 31 is a fuel supply passage supplied to the fuel passage 32 toward the injection hole 25.

  The inflow hole 30 is formed so as to extend along the axial direction Z from the position where the stopper 27 of the needle 14 is formed. Therefore, the upper end portion of the inflow hole 30 located in the valve opening direction Z1, that is, the upstream end of the supply passage opens in the valve opening direction Z1. Further, the lower end portion of the inflow hole 30 located in the valve closing direction Z2 is closed. A communication hole 31 that extends in the radial direction of the needle 14 and communicates the inflow hole 30 and the outer space is formed in the inner wall facing the lower end portion of the inflow hole 30.

  Thereby, the fuel that has flowed down to the inner peripheral side of the cylindrical member 11 via the fuel filter 19 flows into the inflow hole 30 formed in the needle 14, and further, the communication hole 31 formed in the lower end portion of the inflow hole 30. To the outside of the needle 14. Thereafter, the fuel flows down the fuel passage 32 formed between the needle 14 and the nozzle holder 13 and flows into the nozzle hole 25 side. The configuration of the supply passage composed of the inflow hole 30 and the communication hole 31 will be described in detail later.

  Next, the drive unit 15 that drives the needle 14 will be described. FIG. 2 is an enlarged cross-sectional view of a portion of the injector 10 in a closed state where the needle 14 is seated. The drive unit 15 drives the needle 14 along the axial direction Z. The drive unit 15 includes a spool 33, a coil 34, a fixed core 35, a magnetic plate 50, a movable core 36, a connector 37, a first spring 39 and a second spring 46.

  The spool 33 is installed on the outer peripheral side of the cylindrical member 11. The spool 33 is formed in a cylindrical shape with resin, and a coil 34 is wound on the outer peripheral side. The coil 34 generates a magnetic force that attracts the movable core 36 to the fixed core 35 when energized. The coil 34 is electrically connected to the terminal portion 38 of the connector 37. The terminal portion 38 is electrically connected to an external electric circuit (not shown) attached to the connector 37, and the energization state of the coil 34 is controlled by the external electric circuit.

  The fixed core 35 is fixed to a predetermined installation position on the inner peripheral side of the coil 34 with the cylindrical member 11 interposed therebetween. The fixed core 35 is formed in a cylindrical shape from a magnetic material such as iron, and is fixed to the inner peripheral side of the cylindrical member 11 by, for example, press fitting. The magnetic plate 50 is made of a magnetic material and covers the outer peripheral side of the coil 34.

  The movable core 36 is installed on the inner peripheral side of the cylindrical member 11 and the inner peripheral side of the large-diameter portion 20 of the nozzle holder 13 so as to be capable of reciprocating in the axial direction Z. The movable core 36 is formed in a cylindrical shape from a magnetic material such as iron. A first spring 39 is disposed in the fixed core 35. The first spring 39 has one end in contact with the needle 14 and the other end in contact with the adjusting pipe 40. The first spring 39 has a force that extends in the axial direction Z. Therefore, the movable core 36 and the needle 14 are pressed by the first spring 39 in the valve closing direction Z2 that is seated on the valve seat 29. The adjusting pipe 40 is press-fitted into the inner peripheral side of the fixed core 35. Thereby, the load of the first spring 39 is adjusted by adjusting the press-fitting amount of the adjusting pipe 40. When the coil 34 is not energized, the movable core 36 and the needle 14 are pressed in the valve closing direction Z2, and the seal portion 28 is seated on the valve seat 29.

  As described above, the drive unit 15 includes the fixed core 35 and the movable core 36. The needle 14 is inserted into the movable core 36. The movable core 36 is formed with an insertion hole penetrating in the axial direction Z at a central portion in the radial direction. An inner peripheral surface portion (hereinafter also referred to as “hole portion”) 41 facing the insertion hole is formed so that its inner diameter is slightly larger than the outer diameter of the shaft portion 26 of the needle 14. Therefore, the needle 14 can move in the axial direction Z on the inner peripheral side of the hole 41.

  Further, the outer peripheral surface portion 42 of the shaft portion 26 of the needle 14 is in contact with the hole portion 41 of the movable core 36. Therefore, since the needle 14 is displaced in the axial direction Z while being in contact with the movable core 36, the needle 14 and the movable core 36 slide. Thereby, the needle 14 is guided to move in the axial direction Z by the movable core 36 in a state where sliding resistance (friction force) is always generated by contact with the movable core 36.

  Further, the outer peripheral surface portion 43 on the radially outer side of the movable core 36 is in contact with the inner peripheral surface portion 44 of the cylindrical member 11. In the present embodiment, the outer peripheral surface portion 43 of the movable core 36 that contacts the inner peripheral surface portion 44 of the cylindrical member 11 is a convex portion 43 that protrudes radially outward from the remaining surface portion. The convex part 43 is provided in the edge part of the movable core 36 located in the valve opening direction Z1. Further, the projecting portion 43 is in contact with the cylindrical member 11 and is a portion composed of the nonmagnetic portion 17.

  Therefore, since the convex portion 43 of the movable core 36 is displaced in the axial direction Z while being in contact with the inner peripheral surface portion 44 of the nonmagnetic portion 17, the movable core 36 and the nonmagnetic portion 17 slide. As a result, the movement of the movable core 36 in the axial direction Z is guided by the nonmagnetic portion 17 in a state where sliding resistance (friction force) is always generated.

  A stopper 27 provided on the needle 14 regulates the displacement of the movable core 36 in the valve opening direction Z1. The outer diameter of the stopper 27 is larger than the inner diameter of the hole 41. Therefore, the stopper 27 of the needle 14 is in contact with the end surface portion 45 of the movable core 36 (hereinafter sometimes referred to as “the upper end surface portion 45 of the movable core 36”) located in the valve opening direction Z1. When the stopper 27 and the upper end surface portion 45 of the movable core 36 are in contact with each other, the movement of the needle 14 toward the valve seat 29 (valve closing direction Z2) between the movable core 36 and the needle 14 and the stationary core 35 of the movable core 36 are performed. The relative movement to the side is limited. Accordingly, the stopper 27 of the needle 14 limits excessive relative movement between the movable core 36 and the needle 14. The stopper 27 is reciprocally displaced along the axial direction Z on the inner side of the cylindrical fixed core 35. Therefore, the outer diameter of the stopper 27 is smaller than the inner diameter of the fixed core 35.

  The movable core 36 is in contact with a second spring 46, which is an elastic member, at an end 48 (hereinafter, also referred to as “lower end surface portion 48 of the movable core 36”) located in the valve closing direction Z2. The second spring 46 has a force that extends in the axial direction Z. The second spring 46 has an end located in the valve opening direction Z1 in contact with the movable core 36 and an end located in the valve closing direction Z2 in contact with the nozzle holder 13. The second spring 46 is accommodated in the large diameter part 20 and the medium diameter part 21 of the nozzle holder 13. The connecting portion between the medium diameter portion 21 and the small diameter portion 22 has a step because the inner diameters are different from each other, and a step surface portion 47 with which the end of the second spring 46 located in the valve closing direction Z2 contacts is formed. The inner diameter of the middle diameter portion 21 is selected to be slightly larger than the outer diameter of the second spring 46. Such an intermediate diameter portion 21 reduces the inclination and bending of the second spring 46. Therefore, the pressing force of the second spring 46 can be accurately maintained.

The second spring 46 has a force that extends in the axial direction Z. Therefore, the movable core 36 is pressed against the urging by the fixed core 35 side (opening direction Z1) by the second spring 46. A valve closing force f1 in the valve closing direction Z2 is applied to the movable core 36 via the needle 14 from the first spring 39, and a valve opening force f2 in the valve opening direction Z1 is applied from the second spring 46. In FIG. 2, for easy understanding, a direction in which the valve closing force f <b> 1 and the valve opening force f <b> 2 are not illustrated is illustrated, but the direction in which the valve closing force f <b> 1 and valve opening force f <b> 2 are actually applied is illustrated.

  The valve closing force f1 that is the pressing force of the first spring 39 is set larger than the valve opening force f2 that is the pressing force of the second spring 46. Therefore, in the valve closing state in which the coil 34 is not energized, the needle 14 in contact with the first spring 39 and the movable core 36 in contact with the stopper 27 resists the valve opening force f2 of the second spring 46. It moves to the 25 side (valve closing direction Z2). As a result, in a valve-closed state in which energization of the coil 34 is stopped, the seal portion 28 of the needle 14 is seated on the valve seat 29.

  As described above, in the injector 10 of the present embodiment, as shown in FIG. 2, the nozzle holder 13 forming a part of the housing has a large diameter portion 20, a medium diameter portion 21, and a small diameter portion 22. A movable core 36 is disposed inside the large diameter portion 20. The second spring 46 is disposed inside the large-diameter portion 20 and the medium-diameter portion 21 of the nozzle holder 13, and the end on the counter-injection hole side (the valve opening direction Z1 side) is the lower end surface portion 48 of the movable core 36. The end on the injection hole side (valve closing direction Z2 side) is supported in contact with the stepped surface portion 47 between the medium diameter portion 21 and the small diameter portion 22 of the nozzle holder 13.

  Here, the large diameter portion 20 and the medium diameter portion 21 correspond to the large inner diameter portion, and the small diameter portion 22 corresponds to the small inner diameter portion. Therefore, the nozzle holder 13 that forms a part of the housing includes a small diameter portion 22 that is a small inner diameter portion, and a medium diameter portion 21 that is a large inner diameter portion that has a larger inner diameter than the small diameter portion 22 on the side opposite to the injection hole from the small diameter portion 22. And a fuel passage 32 toward the injection hole 25 between the small diameter portion 22 and the needle 14 that is a valve member, and a medium diameter portion 21 that is a part of the large inner diameter portion. The step surface portion 47 between the small diameter portion 22 and the small inner diameter portion serves as a seat surface that supports the end portion on the injection hole side of the second spring 46 that is an elastic member.

  In the needle 14, an inflow hole 30 and a communication hole 31 corresponding to a supply passage are formed. The inflow hole 30 that is the upstream side passage extends in the axial direction Z, and the communication hole 31 that is the downstream side passage connected to the downstream side of the inflow hole 30 intersects the inflow hole 30 (in the present example, orthogonal). Direction). A plurality of communication holes 31 are provided, and in this example, two communication holes 31 are provided in the axially symmetrical position in the needle 14. The needle 14 has a communication hole 31 illustrated in FIG. 2 and a communication hole (not illustrated in FIG. 2) provided on the front side of the drawing with respect to the communication hole 31 (a communication hole having the same shape as the illustrated communication hole 31). ) And are formed.

As is clear from FIG. 2, the diameter of the communication hole 31 having a circular cross section (for example, 1.4 mm) is smaller than the diameter of the inflow hole 30 having a circular cross section (for example, 1.6 mm), but a plurality of communication holes 31 are provided. Therefore, the total cross-sectional area of the communication hole 31 is larger than the cross-sectional area of the inflow hole 30. In other words, the supply passage has a total cross-sectional area of the downstream-side passage (hereinafter simply referred to as “a cross-sectional area of the downstream-side passage”) larger than a cross-sectional area of the upstream-side passage.

  The downstream ends of the plurality of communication holes 31 are all open at a portion between the stepped surface portion 47 of the nozzle holder 13 and the end surface (lower end surface portion 48) of the movable core 36 on the injection hole 25 side in the axial direction Z. doing. Regardless of the displacement position of the needle 14 due to the reciprocating displacement in the axial direction Z for opening and closing the valve, the communication hole 31 of the needle 14 has a downstream end opening position at the step surface portion 47 of the nozzle holder 13 and the injection hole of the movable core 36. It is formed so as to be between the end surface on the 25th side (lower end surface portion 48).

  Next, the operation of the injector 10 with the above configuration will be described with reference to FIG.

  First, the operation when the valve is opened will be described. When energization of the coil 34 is stopped, no magnetic attractive force is generated between the fixed core 35 and the movable core 36. Therefore, the needle 14 is pressed in the valve closing direction Z2 by the valve closing force f1 which is the pressing force of the first spring 39. At this time, the stopper 27 of the needle 14 is in contact with the upper end surface portion 45 of the movable core 36. Therefore, the movable core 36 moves in the valve closing direction Z2 together with the needle 14 in the valve closing direction due to the difference between the valve closing force f1 of the first spring 39 and the valve opening force f2 which is the pressing force of the second spring 46. Thus, the movable core 36 is separated from the fixed core 35. In this way, the seal portion 28 of the needle 14 is seated on the valve seat 29 by moving in the valve closing direction Z2 rather than when the needle 14 is in the valve open state. Therefore, fuel is not injected from the injection hole 25. In this valve-closed state, the lower end surface portion 48 of the movable core 36 is stopped at a position separated from the step surface portion 47.

  As shown in FIG. 3A, when the coil 34 is energized from the closed state at time t1, the magnetic plate 50, the magnetic part 16, the movable core 36, the fixed core 35, and the nozzle holder 13 are caused by the magnetic field generated in the coil 34. Magnetic flux flows and a magnetic circuit is formed. As a result, a magnetic attractive force is generated between the fixed core 35 and the movable core 36. When the sum of the magnetic attractive force generated between the fixed core 35 and the movable core 36 and the valve opening force f2 of the second spring 46 is larger than the valve closing force f1 of the first spring 39, FIG. As shown in (c), the movable core 36 starts moving in the valve opening direction Z1 at time t2. At this time, the needle 14 with which the stopper 27 is in contact with the upper end surface portion 45 of the movable core 36 moves together with the movable core 36 in the valve opening direction Z1. As a result, the seal portion 28 of the needle 14 is separated from the valve seat 29.

  As described above, the fuel that has flowed into the injector 10 from the fuel inlet 18 flows into the fuel filter 19, the inner peripheral side of the inlet member 12, the inner peripheral side of the adjusting pipe 40, the inner peripheral side of the fixed core 35, and the inflow hole 30. Then, the air flows into the inner peripheral side of the nozzle body 24 through the communication hole 31, the inner peripheral side of the medium diameter portion 21, and the inner peripheral side of the small diameter portion 22 in order. The fuel that has flowed into the nozzle body 24 flows into the nozzle hole 25 via the space between the needle 14 and the nozzle body 24 that are separated from the valve seat 29. Thereby, fuel is injected from the nozzle hole 25.

  Thus, not only the magnetic attractive force but also the valve opening force f2 of the second spring 46 is applied to the movable core 36. Therefore, when the coil 34 is energized, the movable core 36 and the needle 14 are quickly moved in the valve opening direction Z1 by the generated magnetic attractive force. Therefore, the operation responsiveness of the needle 14 with respect to energization of the coil 34 can be enhanced. In addition, the electromagnetic attractive force required to drive the movable core 36 and the needle 14 is reduced. Therefore, the drive unit 15 such as the coil 34 can be downsized.

  As described above, when a magnetic attractive force is applied from the valve-closed state, the movable core 36 and the needle 14 move together in the valve-opening direction Z1 when the upper end surface portion 45 of the movable core 36 and the stopper 27 come into contact with each other. . The movable core 36 moves in the valve opening direction Z <b> 1 until time t <b> 3 when the upper end surface portion 45 of the movable core 36 collides with the lower end surface portion 49 of the fixed core 35. When the movable core 36 collides with the fixed core 35, the movable core 36 and the needle 14 can move relative to each other in the axial direction Z. The movement in the valve opening direction Z <b> 1 is continued further away from the upper end surface portion 45. Even if the stopper 27 is separated as described above, the stopper 27 is kept in contact with the first spring 39, so that the stopper 27 does not collide with any other member. Therefore, irregular fuel injection from the nozzle hole 25 is reduced without the needle 14 bouncing.

  Further, when the needle 14 continues to move in the valve opening direction Z1 by the inertial force in the valve opening direction Z1 and the movable core 36 and the stopper 27 are separated from each other, the needle 14 has a second spring via the movable core 36. 46 valve opening force f2 is not applied. Therefore, only the pressing valve closing force f <b> 1 of the first spring 39 is applied to the needle 14. That is, when the movable core 36 and the needle 14 are separated, the force applied to the needle 14 in the valve closing direction Z2 increases. Therefore, excessive movement of the needle 14 in the valve opening direction Z1 is limited, and so-called overshoot is reduced.

  Similarly, when the needle 14 continues to move in the valve opening direction Z1 due to the inertial force in the valve opening direction Z1 and the movable core 36 and the needle 14 are separated from each other, the movable core 36 opens the valve of the second spring 46. The force f2 and the magnetic attractive force are applied, and the valve closing force f1 of the first spring 39 is not applied. That is, when the movable core 36 and the stopper 27 are separated, the force applied to the movable core 36 in the valve opening direction Z1 increases. Therefore, when the movable core 36 collides with the fixed core 35, the movable core 36 does not rebound in the valve closing direction Z2 due to the impact, and at least the coil 34 is energized from time t3 as shown in FIG. 3C. During the period, the state in contact with the fixed core 35 is maintained.

  The impact force when the movable core 36 collides with the fixed core 35 is reduced because the weight contributing to the impact force is reduced (because it is only the weight of the movable core 36). Since the impact force is small in this way, the movable core 36 is extremely difficult to rebound.

  Further, when the needle 14 overshoots and the force applied to the needle 14 is only the valve closing force f1 of the first spring 39, the moving speed of the needle 14 in the valve opening direction Z1 decreases and stops at time t11. After the amount of overshoot becomes maximum, the movement in the valve closing direction Z2 is started by the valve closing force f1. On the other hand, since the movable core 36 is in contact with the fixed core 35 by the magnetic attractive force and the valve opening force f2 of the second spring 46, when the needle 14 moves in the valve closing direction Z2, it contacts the fixed core 35. Movement in the valve closing direction Z2 is restricted by the movable core 36. As a result, the magnetic attraction force and the opening force f2 of the second spring 46 are again applied to the needle 14, so that the needle 14 can maintain the valve opening state. Thus, since the movable core 36 and the needle 14 are relatively movable, irregular fuel injection from the nozzle hole 25 due to the bounding of the needle 14 is reduced. Therefore, even when the energization time to the coil 34 is short, the amount of fuel injected from the nozzle hole 25 can be precisely controlled.

  Next, the operation when the valve is closed will be described. As shown in FIG. 3A, when energization to the coil 34 is stopped at the time t4 from the valve open state, the magnetic attractive force between the fixed core 35 and the movable core 36 disappears. Thereby, the needle 14 starts moving in the valve closing direction Z2 from the time t5 together with the movable core 36 by the valve closing force f1 of the first spring 39. Therefore, the seal portion 28 of the needle 14 is again seated on the valve seat 29, and the flow of fuel between the fuel passage 32 and the injection hole 25 is blocked. Therefore, the fuel injection ends.

  When energization of the coil 34 is stopped at time t4, the movable core 36 and the needle 14 move in the valve closing direction Z2 against the valve opening force f2 of the second spring 46 by the valve closing force f1 of the first spring 39. To do. When the seal portion 28 of the needle 14 is seated on the valve seat 29, the needle 14 tries to rebound in the valve opening direction Z1 due to the impact of the collision. Here, since the movable core 36 and the needle 14 are relatively movable, even if the seal portion 28 of the needle 14 is seated on the valve seat 29, the movable core 36 is closed as it is due to the inertial force in the valve closing direction Z2. The movement in the valve direction Z2 is continued, and the movable core 36 and the needle 14 are separated.

  Therefore, only the valve closing force f 1 of the first spring 39 is applied to the needle 14, and only the valve opening force f 2 of the second spring 46 is applied to the movable core 36. Accordingly, when the movable core 36 and the needle 14 are separated from each other, the resultant force acting on the needle 14 is only the valve closing force f1, and the needle 14 is prevented from rebounding in the valve opening direction Z1. Thereby, when the energization to the coil 34 is stopped, the fuel injection from the nozzle hole 25 is quickly stopped. Therefore, irregular fuel injection is reduced, and the amount of fuel injected from the nozzle hole 25 can be precisely controlled.

  The impact force when the needle 14 collides with the valve seat 29 is reduced because the weight contributing to the impact force is reduced (because it is only the weight of the needle 14 minutes). Thus, since the impact force is small, the needle 14 is extremely difficult to rebound.

  As shown in FIG. 3B, when the needle 14 is seated at time t6, as shown in FIG. 3C, the movable core 36 in which the needle 14 is relatively displaceable is inertial in the valve closing direction Z2. The force overcomes the valve opening force f2 of the second spring 46 that urges the movable core 36 in the valve opening direction Z1, and further displaces excessively in the valve closing direction Z2, so-called undershoot.

  When the movable core 36 undershoots and the force applied to the movable core 36 is only the valve opening force f2 of the second spring 46, the moving speed of the movable core 36 in the valve closing direction Z2 decreases and stops at time t12. After the undershoot amount becomes maximum, the movement in the valve opening direction Z1 is started by the valve opening force f2. On the other hand, the needle 14 is in a state where the seal portion 28 is seated on the valve seat 29 by the valve closing force f <b> 1 of the first spring 39. The movable core 36, which moves in the valve opening direction Z1 by the valve opening force f2, is stopped by the movement of the needle 14 being restricted by the stopper 27 of the needle 14, and enters a valve closing state in which the next valve opening operation can be started.

  Before, the communication hole 31 of the needle 14 has a downstream end opening position at the step surface portion 47 of the nozzle holder 13 and the movable core 36 regardless of the displacement position of the needle 14 due to the reciprocal displacement in the axial direction Z for opening and closing the valve. It has been described that it is formed so as to be between the end surface (lower end surface portion 48) on the nozzle hole 25 side. This is because the communication hole 31 of the needle 14 is in any state when the needle 14 and the movable core 36 are displaced as illustrated in FIGS. That is, the downstream end opening position is formed between the stepped surface portion 47 of the nozzle holder 13 and the end surface (lower end surface portion 48) of the movable core 36 on the nozzle hole 25 side. In other words, even when the needle 14 is overshooted at time t11 or when the movable core 36 is undershooted at time t12, the communicating hole 31 of the needle 14 has its downstream end opening position at the stepped surface portion 47 of the nozzle holder 13 and the movable core. 36 is formed so as to be between the end surface (lower end surface portion 48) on the nozzle hole 25 side.

  According to the above-described configuration and operation, the downstream end of the fuel supply passage formed in the needle 14 has a stepped surface portion of the nozzle holder 13 in the axial direction regardless of the axial displacement position of the needle 14 due to reciprocal displacement. An opening is formed at a position between the end face of the movable core 36 on the nozzle hole 25 side. Therefore, the downstream end of the supply passage is always open toward the second spring 46 storage space (so-called spring chamber) inside the nozzle holder 13. Thus, by opening the downstream end of the supply passage into the large-capacity second spring 46 housing space having a larger cross-sectional area than the downstream fuel passage 32, the fuel pressure when the needle 14 opens and closes. Pulsation can be reduced.

  When the needle 14 is opened, the fuel pressure in the fuel passage 32 is lowered with the start of fuel injection from the nozzle hole 25. When the needle 14 is closed, the fuel injection from the nozzle hole 25 is stopped. The fuel pressure in the fuel passage 32 increases. When the downstream end of the supply passage in the needle 14 is directly open to the fuel passage 32 without using the second spring 46 storage space having a relatively large volume as in the present embodiment, the fuel pressure associated with the on-off valve It is difficult for the lowering or rising of the to converge quickly and pulsation is likely to occur. On the other hand, according to the present embodiment, although the cross-sectional area of the supply passage is smaller than that of the fuel passage 32, the fuel passage 32 and the supply passage communicate with each other via the second spring 46 storage space. The decrease or increase of the fuel pressure in the fuel passage 32 due to the valve is quickly settled as the second spring 46 storage space becomes a buffer space and is unlikely to pulsate.

  Further, in the supply passage in the needle 14, the cross-sectional area of the communication hole 31 that is the downstream side passage is larger than the cross-sectional area of the inflow hole 30 that is the upstream side passage. Accordingly, the passage cross-sectional area upstream of the fuel passage 32 gradually decreases toward the upstream side in the order of the second spring 46 storage space, the communication hole 31, and the inflow hole 30. Thereby, since the site | part whose passage cross-sectional area is sharply restrict | squeezed toward the upstream is not formed, the pulsation of fuel pressure can be reduced reliably. The supply passage is bent in the needle 14, but the cross-sectional area of the downstream passage is larger than the cross-sectional area of the upstream passage at the connection point between the inflow hole 30 and the communication hole 31. Therefore, the pulsation of the fuel pressure can be more reliably reduced.

  Further, the downstream passage of the supply passage is constituted by a plurality of communication holes 31. Therefore, it is possible to easily form a configuration in which the cross-sectional area of the downstream passage in the supply passage in the needle 14 is larger than the cross-sectional area of the upstream passage.

(Other embodiments)
The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the embodiment described above, the fuel supply passage in the needle 14 has a cross-sectional area of the communication hole 31 that is the downstream-side passage larger than a cross-sectional area of the inflow hole 30 that is the upstream-side passage. Is not limited to this, the upstream side passage and the downstream side passage may have the same cross-sectional area, and the cross-sectional area of the downstream side passage may be equal to that of the upstream side passage. It may be smaller than the cross-sectional area.

  In the above-described embodiment, the fuel supply passage in the needle 14 includes the inflow hole 30 that is the upstream side passage and the communication hole 31 that is the downstream side passage, and has two communication holes 31. One or more than three may be used.

  In the above-described embodiment, the fuel supply passage in the needle 14 has the inflow hole 30 that is the upstream side passage and the communication hole 31 that is the downstream side passage orthogonal to each other. If it is. For example, the inflow hole 30 that is the upstream side passage may extend in the needle axial direction, and the communication hole 31 that is the downstream side passage may extend in a direction inclined in both the axial direction and the radial direction.

  In the above embodiment, the nozzle holder 13 includes the large diameter portion 20, the medium diameter portion 21, and the small diameter portion 22, and the second spring 46 storage space is formed inside the large diameter portion 20 and the medium diameter portion 21. The fuel passage 32 is formed inside the small-diameter portion 22, and the large-diameter portion 20 and the medium-diameter portion 21 correspond to the large-diameter portion as referred to in the present invention, and the small-diameter portion 22 corresponds to the small-diameter according to the present invention. It was explained that it corresponds to the inner diameter part. However, the nozzle holder 13 is not limited to one having three types of diameter portions. For example, the nozzle holder 13 has a structure having a large diameter portion corresponding to the large inner diameter portion and a small diameter portion corresponding to the small inner diameter portion, a second spring 46 storage space is formed inside the large diameter portion, and the inside of the small diameter portion is formed. Alternatively, the fuel passage 32 may be formed.

  In the above embodiment, the tubular member 11 and the nozzle holder 13 constitute the housing. However, the present invention is not limited to this. For example, the housing may be constituted by three or more members. .

  In the above embodiment, the injector 10 is applied to a direct-injection gasoline engine, but is not limited to a direct-injection gasoline engine, and is applied to a port-injection gasoline engine, a diesel engine, or the like. May be.

It is sectional drawing which shows the structure of the injector 10 which is a fuel injection valve in one Embodiment to which this invention is applied. 2 is a cross-sectional view showing a main structure of an injector 10. FIG. It is a time chart which shows the relationship between the energization state to a coil, a needle position, and a movable core position, (a) shows a coil energization state, (b) shows a needle position, and (c) shows a movable core position.

Explanation of symbols

10 Injector (fuel injection valve)
11 Tube member (part of housing)
13 Nozzle holder (part of housing)
14 Needle (Valve member)
20 Large diameter part (part of large internal diameter part)
21 Medium diameter part (part of large internal diameter part)
22 Small diameter part (small inner diameter part)
25 Injection hole 27 Stopper 30 Inflow hole (part of supply passage, upstream passage)
31 Communication hole (part of supply passage, downstream passage)
32 Fuel passage 34 Coil 36 Movable core 46 Second spring (elastic member)
47 Stepped surface portion 48 End portion (lower end surface portion, end surface on the nozzle hole side of the movable core)

Claims (2)

By away seated against the valve seat by reciprocally displaced in the axial direction, and the valve member by opening and closing the nozzle hole intermittently the injection of fuel from said injection hole,
The spray hole-opposite end of the valve member, the axial direction is provided movable relative to the valve member, towards the fixed core of said axial spray hole-opposite by being energized coil A movable core that is magnetically attracted;
A stopper that protrudes radially outward at the end of the valve member on the side of the anti-injection hole, and that can come into contact with the surface of the movable core on the side of the anti-injection hole;
An elastic member provided on the nozzle hole side of the movable core and biasing the movable core toward the counter nozzle hole;
A housing for accommodating the movable core movably in the axial direction,
The housing has a small inner diameter portion, and a large inner diameter portion that is provided on the counter-injection hole side from the small inner diameter portion and has a larger inner diameter than the small inner diameter portion, and between the small inner diameter portion and the valve member. And a step surface between the large inner diameter portion and the small inner diameter portion that communicates directly with each other, and a seat surface that supports the end portion of the elastic member on the nozzle hole side. And
The valve member is a fuel injection valve in which a supply passage for fuel supplied to the fuel passage is formed.
The relative movement of the valve member toward the anti-injection hole with respect to the movable core that collides with the fixed core when the valve is opened is defined as overshoot,
The relative movement of the movable core toward the injection hole with respect to the valve member seated on the valve seat when the valve is closed is defined as an undershoot,
The downstream end of the supply passage is independent of the axial displacement position of the valve member due to reciprocal displacement, and the step surface portion in the axial direction of the valve member during the overshoot and the undershoot. A fuel injection valve having an opening at a portion between the end face on the injection hole side of the movable core. The supply passage, an upstream passage extending in the axial direction, and a plurality of downstream passage extending to the downstream end connected to cross to the upstream passage, the total cross-sectional thereof downstream passage The fuel injection valve according to claim 1, wherein an area is larger than a cross-sectional area of the upstream passage.

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